1. Field
Exemplary embodiments of the invention relate to a composition for an alignment layer and a liquid crystal display panel. More particularly, exemplary embodiments of the invention relate to a composition for an alignment layer including a phosphazene compound and a liquid crystal display panel improving a display quality.
2. Description of the Related Art
A liquid crystal display apparatus is one of a flat panel display (“FPD”). Examples of the flat panel display include, but are not limited to, a liquid crystal display (“LCD”), a plasma display panel (“PDP”) and an organic light emitting display (“OLED”).
The liquid crystal display apparatus applies a voltage to molecules of liquid crystals in a liquid crystal cell to adjust the arrangement of the molecules thereby changing optical characteristics such as birefringence, optical activity, dichroism and light scattering, to display an image.
The liquid crystal display apparatus includes a liquid crystal display panel and a backlight assembly. Liquid crystal molecules of the liquid crystal display panel may be aligned in a uniform direction to have uniform brightness and a high contrast ratio.
A reactive mesogen may be included in a liquid crystal layer for aligning liquid crystal molecules. Reactive mesogens may also be included in an alignment layer in order to improve transmissivity and response time of the liquid crystal display. An alignment liquid for forming the alignment layer in a liquid crystal display apparatus may include a polyimide molecule having functional groups such as, a vertical alignment element and a reactive mesogen. Properties of the vertical alignment element and properties of the reactive mesogen are different from each other. Thus, when the alignment liquid is dried, a phase separation may occur, so that the liquid crystal display panel may have smear thereon.
The polyimide molecule is formed from reaction of diamine and anhydride, and the functional groups can be introduced with only diamine. However, the functional groups are too bulky, and as a result, the polymerization time is too long, it is difficult to obtain a polymer having a high molecular weight, and smearing can occur due to the presence of un-reacted monomers. Furthermore, the functional groups are combined with the diamine, and then the diamine reacts with the anhydride. Thus, it is difficult to increase the content of the reactive mesogen in the polyimide. Thus, reactivity of the reactive mesogen may decrease, and as a result, mechanical strength may decrease. Therefore, the formation of an afterimage on the liquid crystal display panel may occur.